Class: HexaPDF::Document

Inherits:
Object
  • Object
show all
Defined in:
lib/hexapdf/document.rb,
lib/hexapdf/document/files.rb,
lib/hexapdf/document/fonts.rb,
lib/hexapdf/document/pages.rb,
lib/hexapdf/document/images.rb,
lib/hexapdf/document/layout.rb,
lib/hexapdf/document/signatures.rb,
lib/hexapdf/document/destinations.rb

Overview

HexaPDF::Document

Represents one PDF document.

A PDF document consists of (indirect) objects, so the main job of this class is to provide methods for working with these objects. However, since a PDF document may also be incrementally updated and can therefore contain one or more revisions, there are also methods for working with these revisions.

Note: This class provides everything to work on PDF documents on a low-level basis. This means that there are no convenience methods for higher PDF functionality. Those can be found in the objects linked from here, like #catalog.

Known Messages

The document object provides a basic message dispatch system via #register_listener and #dispatch_message.

Following are the messages that are used by HexaPDF itself:

:complete_objects

This message is called before the first step of writing a document. Listeners should complete PDF objects that are missing some information.

For example, the font system uses this message to complete the font objects with information that is only available once all the used glyphs are known.

:before_write

This message is called before a document is actually serialized and written.

Defined Under Namespace

Classes: Destinations, Files, Fonts, Images, Layout, Pages, Signatures

Constant Summary collapse

UNSET =

:nordoc:

::Object.new

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io: nil, decryption_opts: {}, config: {}) ⇒ Document

Creates a new PDF document, either an empty one or one read from the provided io.

When an IO object is provided and it contains an encrypted PDF file, it is automatically decrypted behind the scenes. The decryption_opts argument has to be set appropriately in this case.

Options:

io

If an IO object is provided, then this document can read PDF objects from this IO object, otherwise it can only contain created PDF objects.

decryption_opts

A hash with options for decrypting the PDF objects loaded from the IO.

config

A hash with configuration options that is deep-merged into the default configuration (see HexaPDF::DefaultDocumentConfiguration, meaning that direct sub-hashes are merged instead of overwritten.



164
165
166
167
168
169
170
171
172
173
174
175
176
177
 
# File 'lib/hexapdf/document.rb', line 164

def initialize(io: nil, decryption_opts: {}, config: {})
  @config = Configuration.with_defaults(config)
  @version = '1.2'

  @revisions = Revisions.from_io(self, io)
  @security_handler = if encrypted? && @config['document.auto_decrypt']
                        Encryption::SecurityHandler.set_up_decryption(self, **decryption_opts)
                      else
                        nil
                      end

  @listeners = {}
  @cache = Hash.new {|h, k| h[k] = {} }
end

Instance Attribute Details

#config ⇒ Object (readonly)

The configuration for the document.



142
143
144
 
# File 'lib/hexapdf/document.rb', line 142

def config
  @config
end

#revisions ⇒ Object (readonly)

The revisions of the document.



145
146
147
 
# File 'lib/hexapdf/document.rb', line 145

def revisions
  @revisions
end

Class Method Details

.open(filename, **kwargs) ⇒ Object

:call-seq:

Document.open(filename, **docargs)                   -> doc
Document.open(filename, **docargs) {|doc| block}     -> obj

Creates a new PDF Document object for the given file.

Depending on whether a block is provided, the functionality is different:

  • If no block is provided, the whole file is instantly read into memory and the PDF Document created for it is returned.

  • If a block is provided, the file is opened and a PDF Document is created for it. The created document is passed as an argument to the block and when the block returns the associated file object is closed. The value of the block will be returned.

The block version is useful, for example, when you are dealing with a large file and you only need a small portion of it.

The provided keyword arguments (except io) are passed on unchanged to Document.new.



131
132
133
134
135
136
137
138
139
 
# File 'lib/hexapdf/document.rb', line 131

def self.open(filename, **kwargs)
  if block_given?
    File.open(filename, 'rb') do |file|
      yield(new(**kwargs, io: file))
    end
  else
    new(**kwargs, io: StringIO.new(File.binread(filename)))
  end
end

Instance Method Details

#acro_form(create: false) ⇒ Object

Returns the main AcroForm object for dealing with interactive forms.

See HexaPDF::Type::Catalog#acro_form for details on the arguments.



491
492
493
 
# File 'lib/hexapdf/document.rb', line 491

def acro_form(create: false)
  catalog.acro_form(create: create)
end

#add(obj, **wrap_opts) ⇒ Object

:call-seq:

doc.add(obj, **wrap_opts)     -> indirect_object

Adds the object to the document and returns the wrapped indirect object.

The object can either be a native Ruby object (Hash, Array, Integer, …) or a HexaPDF::Object. If it is not the latter, #wrap is called with the object and the additional keyword arguments.

See: Revisions#add_object



228
229
230
231
232
233
234
235
236
237
 
# File 'lib/hexapdf/document.rb', line 228

def add(obj, **wrap_opts)
  obj = wrap(obj, **wrap_opts) unless obj.kind_of?(HexaPDF::Object)

  if obj.document? && obj.document != self
    raise HexaPDF::Error, "Can't add object that is already attached to another document"
  end
  obj.document = self

  @revisions.add_object(obj)
end

#cache(pdf_data, key, value = UNSET, update: false) ⇒ Object

Caches and returns the given value or the value of the given block using the given pdf_data and key arguments as composite cache key. If a cached value already exists and update is false, the cached value is just returned.

Set update to true to force an update of the cached value.

This facility can be used to cache expensive operations in PDF objects that are easy to compute again.

Use #clear_cache to clear the cache if necessary.



430
431
432
433
 
# File 'lib/hexapdf/document.rb', line 430

def cache(pdf_data, key, value = UNSET, update: false)
  return @cache[pdf_data][key] if cached?(pdf_data, key) && !update
  @cache[pdf_data][key] = (value == UNSET ? yield : value)
end

#cached?(pdf_data, key) ⇒ Boolean

Returns true if there is a value cached for the composite key consisting of the given pdf_data and key objects.

Also see: #cache

Returns:

  • (Boolean) 


439
440
441
 
# File 'lib/hexapdf/document.rb', line 439

def cached?(pdf_data, key)
  @cache.key?(pdf_data) && @cache[pdf_data].key?(key)
end

#catalog ⇒ Object

Returns the document's catalog, the root of the object tree.



514
515
516
 
# File 'lib/hexapdf/document.rb', line 514

def catalog
  trailer.catalog
end

#clear_cache(pdf_data = nil) ⇒ Object

Clears all cached data or, if a Object::PDFData object is given, just the cache for this one object.

It is not recommended to clear the whole cache! Better clear the cache for individual PDF objects!

Also see: #cache



450
451
452
 
# File 'lib/hexapdf/document.rb', line 450

def clear_cache(pdf_data = nil)
  pdf_data ? @cache[pdf_data].clear : @cache.clear
end

#delete(ref) ⇒ Object

:call-seq:

doc.delete(ref)
doc.delete(oid)

Deletes the indirect object specified by an exact reference or by an object number from the document.

See: Revisions#delete_object



247
248
249
 
# File 'lib/hexapdf/document.rb', line 247

def delete(ref)
  @revisions.delete_object(ref)
end

#deref(obj) ⇒ Object

Dereferences the given object.

Return the object itself if it is not a reference, or the indirect object specified by the reference.



214
215
216
 
# File 'lib/hexapdf/document.rb', line 214

def deref(obj)
  obj.kind_of?(Reference) ? object(obj) : obj
end

#destinations ⇒ Object

Returns the Destinations object that provides convenience methods for working with destination objects.



478
479
480
 
# File 'lib/hexapdf/document.rb', line 478

def destinations
  @destinations ||= Destinations.new(self)
end

#dispatch_message(name, *args) ⇒ Object

Dispatches the message name with the given arguments to all registered listeners.

See the main Document documentation for an overview of messages that are used by HexaPDF itself.



414
415
416
 
# File 'lib/hexapdf/document.rb', line 414

def dispatch_message(name, *args)
  @listeners[name]&.each {|obj| obj.call(*args) }
end

#each(only_current: true, only_loaded: false, &block) ⇒ Object

:call-seq:

doc.each(only_current: true, only_loaded: false) {|obj| block }
doc.each(only_current: true, only_loaded: false) {|obj, rev| block }
doc.each(only_current: true, only_loaded: false)                       -> Enumerator

Yields every object and the revision it is in.

If only_current is true, only the current version of each object is yielded, otherwise all objects from all revisions.

If only_loaded is true, only the already loaded objects are yielded.

For details see Revisions#each_object



395
396
397
 
# File 'lib/hexapdf/document.rb', line 395

def each(only_current: true, only_loaded: false, &block)
  @revisions.each_object(only_current: only_current, only_loaded: only_loaded, &block)
end

#encrypt(name: :Standard, **options) ⇒ Object

Encrypts the document.

This is done by setting up a security handler for this purpose and populating the trailer's Encrypt dictionary accordingly. The actual encryption, however, is only done when writing the document.

The security handler used for encrypting is selected via the name argument. All other arguments are passed on the security handler.

If the document should not be encrypted, the name argument has to be set to nil. This removes the security handler and deletes the trailer's Encrypt dictionary.

See: HexaPDF::Encryption::SecurityHandler#set_up_encryption and HexaPDF::Encryption::StandardSecurityHandler::EncryptionOptions for possible encryption options.



557
558
559
560
561
562
563
564
 
# File 'lib/hexapdf/document.rb', line 557

def encrypt(name: :Standard, **options)
  if name.nil?
    trailer.delete(:Encrypt)
    @security_handler = nil
  else
    @security_handler = Encryption::SecurityHandler.set_up_encryption(self, name, **options)
  end
end

#encrypted? ⇒ Boolean

Returns true if the document is encrypted.

Returns:

  • (Boolean) 


538
539
540
 
# File 'lib/hexapdf/document.rb', line 538

def encrypted?
  !trailer[:Encrypt].nil?
end

#files ⇒ Object

Returns the Files object that provides convenience methods for working with files.



467
468
469
 
# File 'lib/hexapdf/document.rb', line 467

def files
  @files ||= Files.new(self)
end

#fonts ⇒ Object

Returns the Fonts object that provides convenience methods for working with fonts.



472
473
474
 
# File 'lib/hexapdf/document.rb', line 472

def fonts
  @fonts ||= Fonts.new(self)
end

#images ⇒ Object

Returns the Images object that provides convenience methods for working with images.



462
463
464
 
# File 'lib/hexapdf/document.rb', line 462

def images
  @images ||= Images.new(self)
end

#import(obj) ⇒ Object

:call-seq:

doc.import(obj)     -> imported_object

Imports the given, with a different document associated PDF object and returns the imported object.

If the same argument is provided in multiple invocations, the import is done only once and the previously imoprted object is returned.

See: Importer



261
262
263
264
265
266
267
 
# File 'lib/hexapdf/document.rb', line 261

def import(obj)
  if !obj.kind_of?(HexaPDF::Object) || !obj.document? || obj.document == self
    raise ArgumentError, "Importing only works for PDF objects associated " \
      "with another document"
  end
  HexaPDF::Importer.for(source: obj.document, destination: self).import(obj)
end

#inspect ⇒ Object

:nodoc:



676
677
678
 
# File 'lib/hexapdf/document.rb', line 676

def inspect #:nodoc:
  "<#{self.class.name}:#{object_id}>"
end

#layout ⇒ Object

Returns the Layout object that provides convenience methods for working with the HexaPDF::Layout classes for document layout.



484
485
486
 
# File 'lib/hexapdf/document.rb', line 484

def layout
  @layout ||= Layout.new(self)
end

#object(ref) ⇒ Object

:call-seq:

doc.object(ref)    -> obj or nil
doc.object(oid)    -> obj or nil

Returns the current version of the indirect object for the given exact reference or for the given object number.

For references to unknown objects, nil is returned but free objects are represented by a PDF Null object, not by nil!

See: Revisions#object



190
191
192
 
# File 'lib/hexapdf/document.rb', line 190

def object(ref)
  @revisions.object(ref)
end

#object?(ref) ⇒ Boolean

:call-seq:

doc.object?(ref)    -> true or false
doc.object?(oid)    -> true or false

Returns true if the the document contains an indirect object for the given exact reference or for the given object number.

Even though this method might return true for some references, #object may return nil because this method takes all revisions into account. Also see the discussion on #each for more information.

See: Revisions#object?

Returns:

  • (Boolean) 


206
207
208
 
# File 'lib/hexapdf/document.rb', line 206

def object?(ref)
  @revisions.object?(ref)
end

#pages ⇒ Object

Returns the Pages object that provides convenience methods for working with pages.

Also see: HexaPDF::Type::PageTreeNode



457
458
459
 
# File 'lib/hexapdf/document.rb', line 457

def pages
  @pages ||= Pages.new(self)
end

#register_listener(name, callable = nil, &block) ⇒ Object

:call-seq:

doc.register_listener(name, callable)             -> callable
doc.register_listener(name) {|*args| block}       -> block

Registers the given listener for the message name.



404
405
406
407
408
 
# File 'lib/hexapdf/document.rb', line 404

def register_listener(name, callable = nil, &block)
  callable ||= block
  (@listeners[name] ||= []) << callable
  callable
end

#security_handler ⇒ Object

Returns the security handler that is used for decrypting or encrypting the document, or nil if none is set.

  • If the document was created by reading an existing file and the document was automatically decrypted, then this method returns the handler for decrypting.

  • Once the #encrypt method is called, the specified security handler for encrypting is returned.



574
575
576
 
# File 'lib/hexapdf/document.rb', line 574

def security_handler
  @security_handler
end

#sign(file_or_io, handler: :default, signature: nil, write_options: {}, **handler_options) ⇒ Object

Signs the document and writes it to the given file or IO object.

For details on the arguments file_or_io, signature and write_options see HexaPDF::Document::Signatures#add.

The signing handler to be used is determined by the handler argument together with the rest of the keyword arguments (see HexaPDF::Document::Signatures#handler for details).

If not changed, the default signing handler is HexaPDF::Document::Signatures::DefaultHandler.

Note: Once signing is done the document cannot be changed anymore since it was written. If a document needs to be signed multiple times, it needs to be loaded again after writing.



600
601
602
603
 
# File 'lib/hexapdf/document.rb', line 600

def sign(file_or_io, handler: :default, signature: nil, write_options: {}, **handler_options)
  handler = signatures.handler(name: handler, **handler_options)
  signatures.add(file_or_io, handler, signature: signature, write_options: write_options)
end

#signatures ⇒ Object

Returns an array with the digital signatures of this document.



584
585
586
 
# File 'lib/hexapdf/document.rb', line 584

def signatures
  @signatures ||= Signatures.new(self)
end

#signed? ⇒ Boolean

Returns true if the document is signed, i.e. contains digital signatures.

Returns:

  • (Boolean) 


579
580
581
 
# File 'lib/hexapdf/document.rb', line 579

def signed?
  acro_form&.signature_flag?(:signatures_exist)
end

#task(name, **opts, &block) ⇒ Object

Executes the given task and returns its result.

Tasks provide an extensible way for performing operations on a PDF document without cluttering the Document interface.

See Task for more information.



501
502
503
504
505
506
 
# File 'lib/hexapdf/document.rb', line 501

def task(name, **opts, &block)
  task = config.constantize('task.map', name) do
    raise HexaPDF::Error, "No task named '#{name}' is available"
  end
  task.call(self, **opts, &block)
end

#trailer ⇒ Object

Returns the trailer dictionary for the document.



509
510
511
 
# File 'lib/hexapdf/document.rb', line 509

def trailer
  @revisions.current.trailer
end

#unwrap(object, seen = {}) ⇒ Object

:call-seq:

document.unwrap(obj)   -> unwrapped_obj

Recursively unwraps the object to get native Ruby objects (i.e. Hash, Array, Integer, … instead of HexaPDF::Reference and HexaPDF::Object).



360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
 
# File 'lib/hexapdf/document.rb', line 360

def unwrap(object, seen = {})
  object = deref(object)
  object = object.data if object.kind_of?(HexaPDF::Object)
  if seen.key?(object)
    raise HexaPDF::Error, "Can't unwrap a recursive structure"
  end

  case object
  when Hash
    seen[object] = true
    object.transform_values {|value| unwrap(value, seen.dup) }
  when Array
    seen[object] = true
    object.map {|inner_o| unwrap(inner_o, seen.dup) }
  when HexaPDF::PDFData
    seen[object] = true
    unwrap(object.value, seen.dup)
  else
    object
  end
end

#validate(auto_correct: true, only_loaded: false, &block) ⇒ Object

Validates all objects, or, if only_loaded is true, only loaded objects, with optional auto-correction, and returns true if everything is fine.

If a block is given, it is called on validation problems.

See HexaPDF::Object#validate for more information.



611
612
613
614
615
616
617
 
# File 'lib/hexapdf/document.rb', line 611

def validate(auto_correct: true, only_loaded: false, &block) #:yield: msg, correctable, object
  result = trailer.validate(auto_correct: auto_correct, &block)
  each(only_current: false, only_loaded: only_loaded) do |obj|
    result &&= obj.validate(auto_correct: auto_correct, &block)
  end
  result
end

#version ⇒ Object

Returns the PDF document's version as string (e.g. '1.4').

This method takes the file header version and the catalog's /Version key into account. If a version has been set manually and the catalog's /Version key refers to a later version, the later version is used.

See: PDF1.7 s7.2.2



525
526
527
528
 
# File 'lib/hexapdf/document.rb', line 525

def version
  catalog_version = (catalog[:Version] || '1.0').to_s
  (@version < catalog_version ? catalog_version : @version)
end

#version=(value) ⇒ Object

Sets the version of the PDF document. The argument must be a string in the format 'M.N' where M is the major version and N the minor version (e.g. '1.4' or '2.0').

Raises:

  • (ArgumentError) 


532
533
534
535
 
# File 'lib/hexapdf/document.rb', line 532

def version=(value)
  raise ArgumentError, "PDF version must follow format M.N" unless value.to_s.match?(/\A\d\.\d\z/)
  @version = value.to_s
end

#wrap(obj, type: nil, subtype: nil, oid: nil, gen: nil, stream: nil) ⇒ Object

Wraps the given object inside a HexaPDF::Object class which allows one to use convenience functions to work with the object.

The obj argument can also be a HexaPDF::Object object so that it can be re-wrapped if needed.

The class of the returned object is always a subclass of HexaPDF::Object (or of HexaPDF::Stream if a stream is given). Which subclass is used, depends on the values of the type and subtype options as well as on the 'object.type_map' and 'object.subtype_map' global configuration options:

  • First type is used to try to determine the class. If it is not provided and if obj is a hash with a :Type field, the value of this field is used instead. If the resulting object is already a Class object, it is used, otherwise the type is looked up in 'object.type_map'.

  • If subtype is provided or can be determined because obj is a hash with a :Subtype or :S field, the type and subtype together are used to look up a special subtype class in 'object.subtype_map'.

    Additionally, if there is no type but a subtype, all required fields of the subtype class need to have values; otherwise the subtype class is not used. This is done to better prevent invalid mappings when only partial knowledge (:Type key is missing) is available.

  • If there is no valid class after the above steps, HexaPDF::Stream is used if a stream is given, HexaPDF::Dictionary if the given object is a hash, HexaPDF::PDFArray if it is an array or else HexaPDF::Object is used.

Options:

:type

(Symbol or Class) The type of a PDF object that should be used for wrapping. This could be, for example, :Pages. If a class object is provided, it is used directly instead of the type detection system.

:subtype

(Symbol) The subtype of a PDF object which further qualifies a type. For example, image objects in PDF have a type of :XObject and a subtype of :Image.

:oid

(Integer) The object number that should be set on the wrapped object. Defaults to 0 or the value of the given object's object number.

:gen

(Integer) The generation number that should be set on the wrapped object. Defaults to 0 or the value of the given object's generation number.

:stream

(String or StreamData) The stream object which should be set on the wrapped object.



313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
 
# File 'lib/hexapdf/document.rb', line 313

def wrap(obj, type: nil, subtype: nil, oid: nil, gen: nil, stream: nil)
  data = if obj.kind_of?(HexaPDF::Object)
           obj.data
         else
           HexaPDF::PDFData.new(obj)
         end
  data.oid = oid if oid
  data.gen = gen if gen
  data.stream = stream if stream

  if type.kind_of?(Class)
    klass = type
    type = (klass <= HexaPDF::Dictionary ? klass.type : nil)
  else
    type ||= deref(data.value[:Type]) if data.value.kind_of?(Hash)
    klass = GlobalConfiguration.constantize('object.type_map', type) { nil } if type
  end

  if data.value.kind_of?(Hash)
    subtype ||= deref(data.value[:Subtype]) || deref(data.value[:S])
  end
  if subtype
    sub_klass = GlobalConfiguration.constantize('object.subtype_map', type, subtype) { klass }
    if type ||
        sub_klass&.each_field&.none? {|name, field| field.required? && !data.value.key?(name) }
      klass = sub_klass
    end
  end

  klass ||= if data.stream
              HexaPDF::Stream
            elsif data.value.kind_of?(Hash)
              HexaPDF::Dictionary
            elsif data.value.kind_of?(Array)
              HexaPDF::PDFArray
            else
              HexaPDF::Object
            end

  klass.new(data, document: self)
end

#write(file_or_io, incremental: false, validate: true, update_fields: true, optimize: false) ⇒ Object

:call-seq:

doc.write(filename, incremental: false, validate: true, update_fields: true, optimize: false)
doc.write(io, incremental: false, validate: true, update_fields: true, optimize: false)

Writes the document to the given file (in case io is a String) or IO stream.

Before the document is written, it is validated using #validate and an error is raised if the document is not valid. However, this step can be skipped if needed.

Options:

incremental

Use the incremental writing mode which just adds a new revision to an existing document. This is needed, for example, when modifying a signed PDF and the original signature should stay valid.

See: PDF1.7 s7.5.6

validate

Validates the document and raises an error if an uncorrectable problem is found.

update_fields

Updates the /ID field in the trailer dictionary as well as the /ModDate field in the trailer's /Info dictionary so that it is clear that the document has been updated.

optimize

Optimize the file size by using object and cross-reference streams. This will raise the PDF version to at least 1.5.



647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
 
# File 'lib/hexapdf/document.rb', line 647

def write(file_or_io, incremental: false, validate: true, update_fields: true, optimize: false)
  dispatch_message(:complete_objects)

  if update_fields
    trailer.update_id
    trailer.info[:ModDate] = Time.now
  end

  if validate
    self.validate(auto_correct: true) do |msg, correctable, obj|
      next if correctable
      raise HexaPDF::Error, "Validation error for (#{obj.oid},#{obj.gen}): #{msg}"
    end
  end

  if optimize
    task(:optimize, object_streams: :generate)
    self.version = '1.5' if version < '1.5'
  end

  dispatch_message(:before_write)

  if file_or_io.kind_of?(String)
    File.open(file_or_io, 'w+') {|file| Writer.write(self, file, incremental: incremental) }
  else
    Writer.write(self, file_or_io, incremental: incremental)
  end
end